Technology underlying the design of bicycle components has evolved in recent years. Increasingly, bicycle wheels, hubs, cranks, handlebars, frames and the like, are being designed not only to be sturdy and easy to manufacture, but also to have increasingly lighter weight and improved performance characteristics. A variety of techniques have been used to achieve lighter weights, with most of the design efforts being centered on the choice of materials from which the individual bicycle components are made. In particular, other techniques employed in the manufacture of bicycle hubs include improving the quality of the bearings used in the hubs, and improving the tolerances of the bearing and race assemblies. A typical result of such techniques, for example, may be a reduction in the frictional resistance related to the hub's rotation about the axle of the wheel.
Currently, two primary types of bicycle wheels are used, namely disc and spoke wheels. Examples of disc-shaped wheels include the models 900, 909 and 999 disc wheels sold by Compositech, Inc. of Speedway, Ind. under its ZIPP® SPEED WEAPONRY® brand. An example of such a disc-shaped wheel is also shown in FIGS. 1 and 2 of the Applicant's co-pending Ording '785 Patent. Although the ZIPP Wheels are used mostly on bicycles, they may also be used on other human-powered vehicles such as wheel chairs.
A disc wheel is a wheel that includes a hub at its center and a wheel body having a solid, generally planar disc-shaped surface that extends from the central hub to the perimetral tire engaging surface of the wheel. Although disc wheels are far less commonly used than spoke type wheels, disc wheels are much more aerodynamically efficient wheels and are used by bicycle racers in time trial events, sprint events, and track events, because of their highly prized low aerodynamic resistance properties.
The second typical type of human-powered vehicle wheel is a spoke-type wheel. A spoke-type wheel is disclosed and discussed in Ording and Poertner, U.S. Pat. No. 6,991,298, issued on 31 Jan. 2006, and assigned to the Assignee of the instant invention.
A spoke-type wheel includes an endless ring shaped rim and a central hub. A plurality of spokes extend between the centrally positioned hub and the ring shaped rim to connect the hub and rim, so that the rim is supported about the central hub. Individual spokes may be tightened so that this rim support is kept nearly the same at individual points around the rim. Such a tightening process may be part of a tuning procedure for a wheel that may also include balancing the wheel using weights, alignment, etc. Although spoke-type wheels do not have aerodynamic resistance properties as low as those for disc wheels, they are far more commonly used than disc wheels because they provide better all around performance in non-controlled conditions, such as one would encounter when riding on an open road. For example, a disc wheel may suffer the disadvantage of acting as a “sail” which, because of its large surface area, tends to cause instability for a bicycle when cross winds are encountered.
Common to both wheel types is the use of a hub at the center of the completed wheel.
As noted in the Ording '176 Application, the Applicants discovered that adding surface features to either a disc or spoke-type wheel helps to improve the aerodynamic efficiency of the wheel, by lowering the aerodynamic resistance of the wheel as the wheel moves forward through the air when a bicycle is being ridden.
The Applicants have found that the design and use of aerodynamic surface features in a hub member can also provide significantly improved properties to the bicycle wheel.